The present invention relates to extracorporeal blood treatment circuits, more specifically to a manually operated single-needle apparatus for treating blood, in particular aimed at removing toxins and metabolic products therefrom.
Unlike continuous circulating of blood through a treatment element in the same direction in which the patient's skin and vessels have to be punctured with two separate needles for taking the blood from his or her body and running it back thereto, single-needle blood treatment circuits uses only one needle. Such blood treatment offers the useful effect that the number of punctures is decreased from two to one so that, on the one hand, there is less damage to the vessels while on the other hand pain produced when puncturing the skin is reduced.
Historically, kidney disease has been of critical concern to human life. Many kinds of kidney diseases interfere with the function of the kidney such that the kidney ceases to remove waste and excess water from the blood. When the kidney is sufficiently impaired that a large portion of the waste products and water are not removed from the blood, the life of the patient cannot be preserved unless a way is provided for artificially performing the function of the impaired kidney. Many new developments have come to light, which perform the function of the impaired kidney extracorporeally. Nevertheless, even with the existing improvements in extracorporeal kidney apparatus, the same general procedure is used for processing patients' blood that was used very early in the treatment of kidney disease.
For example, the most commonly accepted practice for treating a patient's blood extracorporeally requires the surgical creation of a subcutaneous, arterio-venous fistula. Thereafter, the subcutaneous venous system dilates secondary to the increase of blood flow derived from the artery to the vein through the fistula. Sufficient blood flow for blood treatment extracorporeally is then obtainable by venipuncture with large bore needles. Normally, two hollow needles or cannulas are used to perform two venipunctures on the patient so that two blood-communication sites exist simultaneously in the patient. Conventionally, blood is withdrawn from one of the punctured blood vessels, forced through a blood treatment circuit and thereafter forced into the other by the use of an extracorporeal pump, typically a peristaltic pump controlled by a sophisticated drive system equipped with a number of pressure sensors.
The aforementioned procedure has been found to have serious disadvantages both to the patient and to the attending physicians and technicians. The problems are particularly aggravated because most patients requiring extracorporeal blood treatment must undergo this treatment as frequently as three to seven times per week. This means that if every venipuncture were completely successful, a patient would need to undergo from 6 to 14 venipunctures or cannulations each week. Besides, in case of an emergency or in the field where this equipment is not available, it is practically impossible to initiate such treatment on a short notice.
It is well known that the duration and proper function of a fistula created by venipuncture is inversely related to the number of venipunctures. Tissue repeatedly subjected to the trauma of venipuncture is much more susceptible to thrombophlebitis, paravascular hemorrhage, clotting and infection. In fact, it is commonly found in patients who have experienced a number of venipunctures, that the tissues surrounding the most accessible veins develop large hematomas which obscure the veins making successful venipuncture extremely difficult because of insufficient blood flow in the damaged blood vessels.
Also contributing to the problem is the fact that once one successful venipuncture is made and blood is allowed to flow from the patient's body toward an extracorporeal blood treatment circuit, the blood volume in the patient's body is reduced making the second venipuncture very difficult. Historically, it has been found that while most skilled physicians or technicians are able to perform the first venipuncture with little difficulty, frequently a plurality of attempts is necessary before a second venipuncture can be performed on the same patient.
To address a number of concerns enumerated above, a single-needle blood treatment circuit was invented. Single-needle systems are known in the art and basically operate by cyclically withdrawing a volume of blood from a patient, passing it through a blood treatment unit, and returning it to the patient. The process then repeats, intermittently processing volumes of blood through the blood treatment unit. A single needle is used for both withdrawing and returning the blood—hence the name. It accomplishes the same result using only one puncture of the vein.
To provide a comprehensive disclosure without unduly lengthening this specification, applicant incorporates by reference in their entireties the disclosures of U.S. Pat. Nos. 3,756,234, 3,830,234, 3,848,592, 3,938,909, 4,063,554, 3,908,653, 3,756,234, 3,811,800, 3,830,234, 3,985,134, 4,490,134, 4,614,590, 4,776,837, 5,358,482, 5,871,459, and 6,074,359 which show various single needle blood treatment devices and teach certain fundamental concepts useful in the construction of a device according to the present invention. They all basically describe a circuit having a single-needle access to the patient's blood system equipped on the back end with a bifurcation to separate the blood flow into two lines. A blood flow loop is then formed starting from one line of the bifurcation and ending with another. A pump and blood treatment apparatus are located along this loop as well as various other devices such as valves, filters, etc.
With all the systems of the prior art however, a complicated piece of equipment is still required to perform a single-needle dialysis. In addition, highly skilled personnel are needed to operate such equipment. Besides, due to dilution or drawing of blood out of the patient during the priming of the circuit, this approach may not be used with neonates or such patients who are sensitive to reduction of blood volume. The need exists to address these limitations of the present day single-needle blood treatment devices.
The situation of acute toxicity for a large number of patients located in the field or another remote site such as for example during war or mass casualties in a terrorist attack presents a special challenge for medical personnel. With the devices available at present time, there is no practical way to initiate the acute extracorporeal blood treatment needed for many people at once in such circumstances. The need exists therefore for an extracorporeal detoxification circuit allowing for blood treatment without the need for electrical power, complicated equipment and highly trained personnel.